Preloader for use in a webbing retractor

A preloader for use in a webbing retractor for retracting an occupant-restraining webbing onto a webbing takeup shaft so as to allow the webbing to be applied to the occupant with appropriate tightness, comprising:

• a frame by which said webbing takeup shaft is rotatably held;
• a rotatable drum disposed in spaced-apart relationship with said webbing takeup shaft for engaging said webbing takeup shaft;
• a plate rotatably supported by said frame such that said rotatable drum is spaced apart from said webbing takeup shaft;
• clamp means having an urging member for constantly urging said clamp means in a direction in which said clamp means clamps an intermediate portion of the webbing, said clamp means being disposed in a state in which said clamp means does not clamp the webbing being drawn out of said webbing takeup shaft, and said clamp means being adapted to prevent the drawing out of the webbing in a clamping state of said clamp means by clamping the intermediate portion of the webbing being drawn out of said webbing takeup shaft;
• trigger means for permitting the movement of said clamp means in the webbing-clamping direction when said plate rotates;
• and
• driving means for causing said rotating drum to deform and engage said webbing takeup shaft when the vehicle suddenly decelerates by applying a radial load to said drum and for rotating said drum and said take-up shaft in a webbing-taking-up direction, and
• a shear pin operatively disposed between said trigger means and said clamp means, wherein said plate is rotated when said drum rotates and said shear pin is broken when a predetermined load or greater is applied to said shear pin by said drum via said plate.

A preloader for use in a webbing retractor for retracting an occupant-restraining webbing onto a webbing takeup shaft so as to allow the webbing to be applied to the occupant with appropriate tightness, comprising:

• a frame by which said webbing takeup shaft is rotatably held;
• an engaging shaft coupled with said webbing takeup shaft;
• a rotatable drum disposed in spaced-apart relationship with said engaging shaft in such a manner as to be capable of engaging said engaging shaft;
• a plate rotatably supported by said frame such that said rotating drum is spaced apart from said engaging shaft;
• clamp means having an urging member for constantly urging said clamp means in a webbing-clamping direction, said clamp means being disposed in such a manner as to be capable of clamping the webbing being drawn out of said webbing takeup shaft, and said clamp means being adapted to prevent the drawing out of the webbing in the clamping state of said clamp means by clamping the webbing being drawn out of said webbing takeup shaft;
• trigger means arranged such that one end thereof is supported by said clamp means, another end thereof abuts against said plate as said plate rotates, and a substantially intermediate portion thereof is supported by said frame, wherein said trigger means permits the movement of said clamp means in the webbing-clamping direction when the vehicle suddenly decelerates;
• and
• a wire member for causing said drum to deform and engage said engaging shaft by applying a radial load to said drum and for rotating said drum and webbing takeup shaft via said engaging shaft in the webbing-taking-up direction when the vehicle suddenly decelerates, and
• a shear pin operatively disposed between said trigger means and said clamp means, wherein said plate is rotated when said drum rotates and said shear pin is broken when a predetermined load or greater is applied to said shear pin by said drum via said plate.